Jui Wen-chun. / Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 64-67.

Call number: LD2668 .T4 1960 Z57

No description available.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Geography / Master / Master of Philosophy

Call number: LD2668 .T4 1986 M375 / Master of Science / Chemistry

A subsurface flow constructed wetland was built at the Wastewater Treatment Plant in Muncie, Indiana, in May, 1995. In May, 1996, this wetland was divided into two equal cells and planted with Scirpus validus vahl (softstem bulrush). Samples were collected from July 30, 1996, through October 22, 1996. This study had two objectives. The first was to determine if harvesting the aboveground biomass of the Scirpus would affect the wetland's ability to remove nitrogen from the wastewater. The second objective of this study was to determine if harvesting the bulrush twice during a growing season would substantially increase the annual biomass production. Water was collected from four locations in each cell and analyzed for organic nitrogen, ammonical nitrogen, nitrate, and total nitrogen. The concentration of each nitrogen parameter was significantly reduced between the inlet and well 1 in each cell of the wetland. There were no significant reductions in nitrogen concentration in subsequent sampling locations. There were also no significant differences between the two wetland cells. / Department of Natural Resources and Environmental Management

Blue Lake, Jefferson County, Oregon, has high summer surface phosphorus concentrations (ca. 30 ug/l) yet is oligotrophic (summer Secchi depth is 11 to 16 meters). Nutrient enrichment experiments done with 1000 1 polyethylene enclosures indicate nitrate limitation of phytoplankton growth. Basin morphology may be an important factor in nutrient cycling in this lake. The lake has a maximum depth of 95.7 meters with an average depth of 42.7 meters. The lake basin has steep sides with only 4% of the lake bottom less than 3.3 meters deep. of recent volcanic origin. In contrast, Suttle Lake, which is immediately downstream from Blue Lake, is moderately eutrophic (Secchi depth 1.7 meters) and supports much larger populations of phytoplankton, including nitrogen fixing cyanophytes. Suttle Lake is shallower and more subject to wind mixing.

The Calapooia River, a major tributary of the Willamette River in western Oregon, is a watershed typical of many found in the Willamette Basin. Public and private forested lands occur in the steep Upper Zone of the watershed, mixed forest and agriculture lands are found in the Middle Zone, and the Lower Zone of the watershed is comprised primarily of grass seed agriculture on relatively flat topography with poorly drained soils. High levels of dissolved nitrogen (DN) have been identified as a water-quality concern within the Calapooia River. To gain a better understanding of the relationship between landuse/landcover (LULC), soil drainage, and DN dynamics within the watershed on a seasonal basis, we selected 44 sub-basins ranging in size between 3 and 33 km² for monthly synoptic surface water-quality sampling from October 2003 through September 2004. We selected an additional 31 sample locations along the length of the Calapooia River to determine relative influence of the 44 sub-basins on DN concentrations in the river. T-tests were used to analyze differences between zones (Upper, Middle and Lower) and regression analysis was used to determine relationships between DN and LULC or soil drainage class. The agriculture-dominated sub-basins had significantly higher (< 0.05) DN concentrations than the predominantly forested sub-basins. Winter concentrations of nitrate-N were 43 times higher in agriculturally dominated sub-basins than in forested sub-basins, whereas in the spring, the difference was only 7-fold. High DN concentrations associated with the predominantly agriculture sub-basins were substantially reduced once they mixed with water in the Calapooia River, highlighting the likelihood that water draining the relatively nutrient-poor, forested sub-basins from the Upper Zone of the watershed, was diluting DN-rich water from the agriculture sub-basins. Relationships between DN and agriculture, woody vegetation or poorly drained soils were moderate to strong (0.50 < R² > 0.85) during the winter, spring and summer seasons. Results indicated an exponential increase in DN concentration when proportion agriculture or poorly drained soils increased, whereas an increase in woody vegetation was related to an exponential decrease in DN concentration. The high variability in DN concentration in the agriculture-dominated sub-basins suggests factors in addition to LULC and poorly drained soils influence DN in surface water. Seasonal relationships were developed between DN and proportion of poorly drained soils, agriculture, and woody vegetation at differing scales (10 m, 20 m, 30 m, 60 m, 90 m, 150 m, 300 m, and entire sub-basin), which we defined as Influence Zones (IZs), surrounding the stream network. Correlations between DN and proportion LULC or poorly drained soil at each IZ were analyzed for significant differences (p-value < 0.05) using the Hotelling-Williams test. Our results show strong seasonal correlations (r > 0.80) between DN and proportion of woody vegetation or agriculture, and moderate-to-strong seasonal correlations (r > 0.60) between DN and proportion of sub-basins with poorly drained soils. Altering scale of analysis significantly changed correlations between LULC and DN, with IZs < 150 m generally having higher correlations than the sub-basin level. In contrast, DN correlations with poorly drained soil were generally higher at the sub-basin scale than the 60- through 10-m IZs during winter and spring. These results indicate that scale of analysis is an important factor when determining relationships between DN concentration and proportion LULC or poorly drained soils. Furthermore, seasonal shifts in significant differences among IZs for correlations between LULC and DN suggest land management proximity and its influence on DN concentration changes temporally. DN relationships with poorly drained soil suggest that during winter and spring, when rainfall is highest, sub-basin scale soil drainage properties have a greater influence on DN than soil properties within IZs in close proximity to the stream network. / Graduation date: 2006

No description available.